J-2X Hot-Fire-Tests First Additive-Manufactured Part

NASA and its SLS partners pull out the stops to reduce costs as hardware testing surges ahead

Facing even greater budgetary uncertainty than before, Aerojet Rocketdyne is entering a key period of testing in its drive to cut cost from the propulsion element of NASA's heavy-lift Space Launch System (SLS) vehicle.

Working closely with the space agency, the newly merged rocket engine company has a raft of cost-saving initiatives underway ranging from production streamlining to advanced, but cheaper, manufacturing methods. According to NASA's SLS liquid engines program manager Mike Kynard, the goal is straightforward. “We want SLS to be more affordable. We don't want to spend all our money on the truck that takes us to space—we want to be able to spend more on exploration when we get there.”

The vision statement stems as much from the fiscal realities of the pressurized NASA budget as it does from the bitter experience of the canceled Constellation program that preceded the SLS. “The Augustine Report said Constellation was not affordable, and we heard that message loud and clear,” Kynard told reporters at NASA Stennis Space Center, Miss., where tests are underway of the liquid-oxygen/hydrogen (LOx/LH) J-2X upper-stage engine in development for the SLS.

The latest hot-fire test of the J-2X on Sept. 5 included the first part made from selective laser melting (SLM), a subset of additive manufacturing. The part tested was an access port cover, not typical of the more complex, hard-to-make parts for which SLM will be generally used. But Aerojet Rocketdyne and NASA officials say its inclusion in the J-2X program helps pave the way for broader applications later. Initial targets include using SLM to help produce a more affordable, expendable version of the SLS's RS-25, which was originally developed as the space shuttle main engine (SSME).

Jim Paulsen, Aerojet Rocketdyne Advanced Space and Launch deputy program manager, says the company needs “to start focusing on affordability, and that's going to be by using lessons learned from the RS68 and J-2X and applying it to the new RS-25.” Paulsen adds, “we hope to get started on that fairly soon because there is a supply-base concern. We hope that when the new fiscal year starts in October we will be working on restarting RS-25 production.”

Kynard says potential applications of SLM include parts that are difficult to manufacture such as the “pogo” LOx splash-baffle, which is designed to prevent potentially damaging frequency harmonics in the fuel system. Company officials say the application of the SLM process is expected to bring significant cost and time savings. Gas-generator components that typically took nine months to produce at a cost of $300,000 are now expected to be made in 3-5 weeks for just $35,000. NASA SLS program manager Todd May says, “we are laser-focused on getting costs down,” and notes that the sintering process is a valuable tool in this initiative.

As well as affordability, the design focus for the new-build RS-25 units will counter obsolescence issues that have emerged over time. An example is the 1980s-vintage engine controller on the SSME. The new-build engine, which will retain the baseline RS-25 designation, is a modern digital-engine controller that will be derived from units tested on the new upper-stage engine.

“J-2X was made for Ares [under Constellation] and that's been adapted for SLS, so now it has different requirements,” says Kynard. “So we are evolving the J-2X controller to control the RS-25. We think it is helpful to have a common engine controller anyway, so as we evolve the J-2X unit for the RS-25, we'll keep an eye on it and see if we can put it in the RS68, and if we resurrect it, the F-1B as well.” The adapted J-2X controller will be run on a pair of RS-25 development engines at Stennis starting next year.

Aerojet Rocketdyne is moving to restart RS-25 production soon because, even though NASA has 15 complete RS-25 former shuttle engines in storage at Stennis and a 16th due to be assembled from existing parts, this will only cover sufficient engines for four launches of the SLS. The first stage of the SLS will use four RS-25s. “The first 16 flight engines are covered, but we like to have four spares ready to go. So you could argue we are good for three launches,” says Paulsen. The first four SLS flights are slated for 2017, 2021, 2023 and 2025. “So we will be looking at delivering the first new engines to Stennis in the 2021-22 time frame,” he adds.

Up to 50% of the cost-savings for the expendable RS-25 is also expected to be realized through the process of “value-stream mapping,” the way the engine is put together. “Part of the close-out of the shuttle involved looking at what it takes to restart RS-25,” says Tom Martin, development lead for the F-1B advanced booster risk-reduction program at Aerojet Rocketdyne. “We did value-stream mapping to see what drove the major costs and, in future, if we restart production, we will hit the ground running.”

“We saw opportunities before where we could do things differently, but change was too expensive in the middle of the shuttle program for re-certification reasons,” adds Chris Sanders, Aerojet Rocketdyne's deputy director for strategic planning and business development.

“After 30 years of work with space shuttle,” Martin says, “there was a lot of baggage that you didn't want to mess with because it was a flight program. So you can look at it now and say, 'What do you want to keep and what don't you need?'”

“We changed the approach because the SSME was made in limited quantities and nobody had ever done value-stream mapping on it before,” says Kynard. “We looked at every step to see if there was a better way to make the engine. Flow time has seen a huge benefit. We're seeing three to four months go to about one-month assembly periods. This engine is ripe for that, and we can make the flow common between engines. That way, the line doesn't care if it's a J-2X or an RS68.”

Under the revised process, the overall time for production of the new RS-25 from long-lead items to installation is expected to be reduced to around four years from the 6.5-year period it saw on the shuttle. “It's ambitious, but that's how you drive affordability,” Kynard adds.

Martin says the focus has been on three major areas: raw materials, touch labor and support labor from engineering staff. “So we've been going through and looking at all of that,” he says. “We've been consolidating the supply chain.”

Sanders says that suppliers that represent a potential single-point failure have been eliminated, while the number that are common between multiple programs is growing. “For example, they are 65% common between the J-2X and RS-25 and it's likely that will go higher.”

As one of the major tenets of SLS is the heavy use of heritage hardware, Sanders believes this also plays a role in forcing the government-industry team to seek even more cost-saving initiatives. “NASA decided to go with mature and relatively low-risk technology, so we've inserted in J-2X more modern manufacturing, and the facilities have been laid out to optimize the production and assembly flow,” he says.

“So at the program level, we've got those kinds of things going on. At the company level, we've been reducing our footprint at the various campuses, which is down by 50% since we started the process in 2007,” Sanders notes. “Head-count is also down by around 30% and part of that is the new reality of the business base—as well as a drive to be leaner and more affordable.”

Sanders says this is not just about “reducing square footage.” The company has also been “making efforts to consolidate large turbomachinery production into one location [at West Palm Beach, Fla.], and at Stennis, where we conduct all large-engine assembly and test. In one site, there is now RS68, RS-25 and J-2X,” he says.

Major manufacturing consolidation is also close to completion at Aerojet Rocketdyne's site in De Soto, Calif., near Los Angeles, where the company has centralized activity away from the heritage facility at nearby Canoga Park. “That's the third big part. We've laid out assembly and flow to minimize production time and unnecessary flow,” Sanders says.

“We are trying to use same manufacturing technology so that in a common shop the same people can work on different parts. For example, the move to hip-bonded chambers, which was implemented on the J-2X, is a good example of where it sets the stage for everything we're doing on RS-25,” he says. “We use it on RS68 and intend to use it on the F-1B. In many ways, the J-2X is a testbed for everything we need to do for the RS-25. Also, the RS-25 is a restart of an existing production line, just like J-2X.”

Sanders stresses that the “SLS will only be successful if it is affordable.” He asserts that “this program, more than any previous shuttle replacement effort, has the greatest chance because of the initiatives that are being taken now.”